sql - Oracle日期差异与案例

Question

我有以下内容：

 select nvl ( 
     (select 1
      from tableA, tableB 
      where tableA.id(+) = 9999
      and tableB.project_id(+) = tableA.project_id
      and sysdate - tableA.start_date < 120), 0) as myFlag from dual;

我正在尝试查看项目开始日期是否小于 120。上面的查询有效，但有更好的方法吗？就像案例陈述一样？

Answer 1

select 
  case 
      when sysdate-tableA.start_date < 120 then 1
      else 0
  end myFlag
from tableA, tableB 
where tableA.id(+) = 9999
and tableB.project_id(+) = tableA.project_id

Answer 2

你为什么要加入表 B？你就不能这样做吗？

SELECT CASE WHEN ID IS NULL THEN 0 ELSE 1 END
FROM TableA 
WHERE sysdate - TableA.start_date < 120 and TableA.id = 9999;